WHAT IS BIOSTRATIGRAPHY AND WHY DO WE DO IT?
The rocks at the Earth's surface, and beneath our feet - the "subsurface" - can be characterised and organised based not just on the type of rock they are, but also on the fossils they contain (where the two parts; "bio-" and "-stratigraphy" come from). By analysing the fossils in the rock we can estimate the rock's age and also we can also discover something about the environment in which the sediments that make up that rock were laid down. The fossils that biostratigraphers use to do this can range in size from huge sauropod skeletons, tens of metres in size, right down to an individual grain of pollen, invisible to the naked eye.
We know that some fossil species existed for several million years before they became extinct and that other species may have existed only for a few hundreds of thousands of years during Earth's long and varied history. If we find these fossil species in our rocks we can often date those rocks to within fairly precise time ranges. More importantly, if we find that same fossil species at two or more different localities on Earth, we can correlate (join) those occurrences and begin to drawn up maps of the subsurface because we can "join the dots" between our fossil species occurrences and link together rocks that might be far apart but that were deposited at the same time.
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These correlations are useful because we often need to know how the rocks beneath our feet are arranged. We may, for example, want to build a dam or a bridge and we need to know if the foundation rocks beneath the soil are hard and stable, or soft and crumbly. We may want to know if an offshore wind-farm can be sited in a suitable area for similar reasons. And yes, even in these days where we are trying to reduce our dependency of fossil fuels, we still need to know the best places for siting the positions of new oil and gas wells and how to produce hydrocarbons with a lower carbon footprint than we have done before. Biostratigraphy is a critical tool in our toolbox needed to understand the subsurface. Biostratigraphy revolves around the knowledge of fossils. Because many of the rock samples biostratigraphers analyse are relatively small, or come from drilled boreholes where much of the rock is smashed up into very small fragments, the fossils many biostratigraphers work with are also small - so small in fact that we have to use microscopes to see them. |
These "microfossils" come from a large variety of animal and plant origins which make up a microscopic world of their own and which often passes us by, unnoticed. Many species of microfossils are living today - two or three groups are hugely important to life on Earth today and in the geological past, as they provide most of Earth's breathable oxygen. Many others are from organisms that occupy relatively low places in the "food web" and are vital for the existence of larger animals that feed on them. Some microfossil groups come from types of organisms that are now extinct on Earth, including one form of microfossil that is believed to be mouth parts of an extinct eel-like creature that was one of our oldest ancestors!
All these microfossils are less than 1mm in size and, in the case of the nannoplankton and pollen, less than 0.01mm
EVOLUTION MAKES IT WORK!
The reason there are so many different forms of life on Earth - and the reason we have many microfossil groups and species that have lived and died throughout Earth's history - is because of evolution. Paleontologists noted long ago that many fossils they found in rocks didn't look anything like the animals (and plants) that live on Earth today, whereas some looked remarkably similar! Most people thought that the unfamiliar fossils were wiped out during the biblical flood ("Noah's flood"), while the familiar fossils survived, because they could not imagine an Earth that was older than just a few thousand years and could not imagine events which occurred before those mentioned in the bible.
A Scottish gentleman and geologist, James Hutton - himself a religious man - realised from looking at the arrangement of some of the rocks in Scotland that there must have been vastly long time-periods involved in order to arrange the rocks in the configurations we see in the present day. He presumed that the age of the Earth should be measured in millions of years (and even hundreds of millions of years) rather than just a few thousand as the bible suggested. You can see some of Hutton's rocks and watch a video of Hutton and his story on our website's front page.
| About 30 years after James Hutton's time a young naturalist from Shrewsbury called Charles Darwin set sail on a five-year voyage around the world which would show - among other things - that members of species were not all absolutely identical and that, in some cases, species would look slightly different if they could be observed in different places, say, on different islands. Darwin wondered why they were different and concluded that different features on the different islands favoured the development of certain characteristics in the animals and plants living on them. |
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For example, tortoises with long necks were good at feeding on leaves from bushes of medium height off the ground, whereas tortoises with shorter necks fed on leaves and grass closer to the ground. The vegetation, in turn, depended on how well watered each island was. Darwin wondered if animals could adapt to the different environments each island had to offer. If they did, did they consciously change to suit the conditions or was it something they had no conscious control over? How long did it take to change? What happened to those that couldn't or didn't change?
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Darwin eventually concluded that those individuals that were slightly different from their fellows - say, an individual with a slightly longer neck - would have a slightly better chance of surviving during dry periods when ground vegetation disappeared and only bush-like cactuses would grow. If an individual survived the drought, it would pass on that trait of having a slightly longer neck to its offspring who would, in turn, have a slightly better chance of surviving the next drought and passing on their long-necked trait, and so on... Darwin worked out that these small incremental changes must take place over very long time-spans in order for them to make a difference to survival and to create a brand new species of long-necked tortoise; time-spans far longer than than the two or three thousand years the biblical flood would allow. James Hutton's theories - and those that followed him - on the age of the Earth, gave Darwin the time he needed to allow for his changes (which he called "Natural Selection") to take place. |
Of course, we now know these small variations between individuals of the same species are caused by mutations in the organism's DNA and variations caused by the "mixing" of DNA between the parents. If favourable, these mutations or differences (like a slightly longer neck) could be passed on to the organism's offspring. Darwin knew about the principles of inheritance of certain characteristics from the organism's parents (including us!) but he did not know of the mutation mechanism. Nevertheless his conclusions were revolutionary and he has become one of the most influential humans in history.
Small changes, but operating over millions of years, have resulted in the diversity of life we see on Earth today, and during the geological past. It also gives us our grand mosaic of a huge variety of different species that lived during a huge variety of different time periods. It is this vast reservoir of fossil species that allows the biostratigrapher to operate.
Want to find out more? We run short training courses on how Biostratigraphy can be applied throughout many practical situations. Click here to see the Supplementary Notes that accompany our training courses. These are of a much more technical nature.
Welcome to GSS Geoscience Ltd.
GSS Geoscience Ltd. and its forerunner GSS International, formed in October 1993, has been serving the international energy industry for 32 years as an independent company!
The main image shows "Hutton's Unconformity" at Siccar Point, eastern Scotland - one of the fundamental pillars on which modern Geoscience is based. Slightly tilted reddish Devonian rocks (left) lie above almost vertical grey older Silurian sediments (lower right). The surface between them represents a time-gap of 65 million years and James Hutton (a Scottish "natural philosopher" of the 18th century) instantly changed our perceptions about the age of the Earth - until then though to be around 6,000 years old - and the role time plays in geology. Hutton realised that the Silurian rocks had to have been deposited, buried, lithified, uplifted and strongly tilted (by mountain-building events similar to those that built today's Himalayan Mountains), then eroded and re-submerged before the Devonian sediments could even begin to be laid down across their eroded surface. This sequence of events couldn't possibly have occurred over such a short a time period as 6,000 years. John Playfair, a colleague who accompanied Hutton to the locality in 1788, said "The mind seemed to grow giddy by looking so far into the abyss of time." (Photo credit: John Van Hoesen)
View a short BBC film about James Hutton and his unconformity here.
Current GSS projects include continuing our active research programme on the Cenomanian and Turonian stages of the Cretaceous period. Papers on Cenomanian Larger Benthic Foraminifera have recently been published (2023-24) in Acta Palaeontologica Romaniae, following our review of Cenomanian planktonic foraminifera published in Newsletters on Stratigraphy in 2022. An expanded series of paper on Cenomanian LBF, and and even wider review of Cenomanian biostratigraphy are in progress Go to our Research page for details and to download PDFs of our latest published research.
Another Dinosaur Killer? Not exactly, but...
What would a geology website be without the obligatory article on dinosaurs?! There can be few people on the planet who are unaware of the sad fate of the dinosaurs who "ruled the world", brought to sudden extinction by the impact of a large asteroidal body 66 million years ago and marked the end of Cretaceous times. We now know this asteroid fell to Earth near the Yucatan Penninsula in Mexico, but for a while there was another candidate for the impact - a smaller one - having occurred in Northwest Europe. This impact crater - known as the "Silverpit" Crater - was only discovered in the early 2000s, not only because it is located beneath the waters of the North Sea, but also that it occurs almost a kilometer below the sea-bed and was detected by seismic imaging. Its basic position suggested it occurred very close to the junction between two rock series whose boundary is coincident with the Cretaceous-Tertiary extinction event. Was this the "dinosaur-killer", or at least perhaps related to it? A research paper to be published soon which involves GSS Geoscience's Mike Bidgood tells the story in full, but click here for an informal article...
A new Masters-level course in Applied Micropaleontology is being set up in Athens beginning in the Fall Semester 2025. Mike Bidgood and research associates Mike Simmons (Halliburton & the NHM), Emma Sheldon (GEUS) and Matt Wakefield (Lealt Stratigraphy Ltd.) are pleased to be associated as Advisors to the course. Applications will open in January 2025. Click the image to go to the website.
NEW PAPERS 2025!
As the year begins, the second in a new series of papers on Cenomanian LBF has been submitted for review. This part concerns the "Loftusiids" and their identities and biostratigraphies are reviewed. This follows on from last year's published paper on the "Nezzazatoid" group. The work is a collaborative effort between Mike Simmons & Mike Bidgood, together with Lorenzo Consorti of ISMAR-CNR, Trieste, and Felix Schlagintweit of Munich (and GSS associate) and is the second of a total of 7 anticipated future papers on this subject. A PDF of the review manuscript will be placed on our Research page shortly.
We are also involved in a re-evaluation of current UK Applied Biostratigraphic training at postgraduate level, involving the GeoNetZero Centre for Doctoral Training, The Micropaleontological Society and the Geological Society of London.
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A group of NERC-CDT doctoral students interpreting the sequence stratigraphy of a well from the Gulf of Mexico.
Fortunately, in the bigger picture, none of these things are critical when it comes to understanding how biostratigraphy can help you find more energy sources. They can be left to the specialist.
However... understanding how biostratigraphy "fits" into the exploration workflow and life cycle of a precious asset is important.
We can guide you through the grey, technical "fog". We can show you why and how biostratigraphy can be applied at numerous points along the screening-exploration-development-production workflow without worrying about the identification of fossils or their strange names. Topics covered include:
- Biostratigraphy in basic-screening and exploration
- Constructing chronostratigraphic charts and gross depositional environment (GDE) maps
- Biostratigraphy in sequence stratigraphy - prediction of the subsurface and identifying new plays
- Biostratigraphy in sequence stratigraphy - identifying and characterising surfaces and systems tracts
- Biostratigraphy in appraisal
- Biostratigraphy in production - at the wellsite; monitoring, "geostopping" and "biosteering"
Mike Bidgood and Associates have also provided these courses to young people about to enter the Energy Industry at both Masters degree and Doctoral level at the following institutions: The Universities of Aberdeen (UK), Bonn (Germany), Brunei, Chulalongkorn (Bangkok, Thailand), Heriott-Watt (UK), Imperial College (UK), Manchester (UK) and Royal Holloway (UK) and in various localities for NERC-CDT (Centre for Doctoral Training). We have also provided short-courses in Applied Biostratigraphy for AAPG in London.
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Dr Mike Simmons is Technology Fellow for Geosciences and the Energy Transition for Halliburton Inc. He is a global thought-leader on industry-related geoscience topics such as sequence stratigraphy, sea-levels; their magnitudes and timing, basin analysis, large-scale and dimensionless geoscience databases, predictions using AI & ML and, not least, the Energy Transition. Formerly 17 years with BP and subsequently at Aberdeen University and chief geoscientist at CASP, Mike was a co-founder and Director of Neftex Geological Consultants Ltd. in 2001. Mike is also a trained biostratigrapher and is a key colaborating partner on many aspects of GSS Geoscience's research. Mike is senior- and co-author of many papers listed below, for example. Mike Simmons and Mike Bidgood are currently focussing on the biostratigraphic aspects of the Mid Cretaceous, in particular the Cenomanian (where they have recently published reviews on the planktonic and the "larger benthic" foraminiferal biostratigraphy), and the Turonian and Coniacian stages. They are also involved in ongoing research centering on the Cenozoic evolution of the Thrace Basin and Western Black Sea Basin of Paratethys. |
In Preparation/Press:
Simmons, M.D. & Bidgood, M.D. Cenomanian larger benthic foraminifera - a stratigraphic review. [an assessment of the validity of published data to evaluate the identity and stratigraphy of LBF recorded from Cenomanian strata - an extension paper to our 2023 review of "planispiral" forms, this data includes the assessment of over 100 species and which will be published as a series of papers covering separate taxonomic groups]
Simmons, M.D. & Bidgood, M.D. Cenomanian marine biostratigraphy: a review. [a review, comparison and integration of the stratigraphy of numerous fossil groups e.g., ammonites, inoceramids, foraminifera, nannofossils, palynomorphs, bivalves, ostracods, microcrinoids, radiolaria, together with radiometric dating, isotope curves and sea-levels]
Published:
Bidgood, M.D., Schlagintweit, F., & Simmons, M.D. 2024. The genus Orbitolina d'Orbigny, 1850 (Larger Benthic Foraminifera) and its constituent species: notes on identity and stratigraphic ranges. Acta Palaeontologica Romaniae, 20 (2), 33-59.
Mahboubi, C.Y., Naimi, M.N., Simmons, M.D. & Bidgood, M.D., 2024. Algal microfacies in the Theniet Et Temar Formation (middle Oxfordian), Central Saharan Atlas, Algeria. Proceedings of the Geologists' Association,135 (1), 78-88.
Simmons, M.D. and Bidgood, M.D., 2022. Hemicyclammina whitei (Henson, 1948): The senior synonym of Hemicyclammina sigali Maync 1953, a distinctive larger benthonic foraminifer from the Mid-Cretaceous of Neotethys. Acta Palaeontologica Romaniae, 19 (1), 27-40.Bidgood, M.D. and Simmons, M.D., 2022. Cenomanian planktonic foraminifera, bioevents and biozonation – A brief review. Newsletters on Stratigraphy, 56 (2), (2023), 125 - 156.Okay et al., 2020. Eocene-Oligocene succession at Kıyıköy (Midye) on the Black Sea coast in Thrace. Turkish Journal of Earth Science, 29, 139-153.Simmons, M.D., Bidgood, M.D., Brenac, P. et al., 1999. Microfossils assemblages as proxies for precise palaeoenvironmental determination - an example from Miocene sediments of northwest Borneo. In: Jones, R. W. & Simmons, M. D. (eds), Biostratigraphy in Production and Development Geology. Geological Society, London, Special Publications, 152, 219-241.
Routine, semi- and fully-quantitative biostratigraphical analysis on single- or multi-well projects:
- Micropaleontology (forams, ostracods, diatoms etc.)
- Nannopalaeontology (calcareous nannoplankton)
- Palynology (dinoflagellates, acritarchs, spores and pollen)
- Development of field, regional, basin and global zonation schemes
- Multi-well correlation
- Sequence stratigraphic modelling
- Basin analysis
- Data review
- Geological Monitoring (exploration wells)
- Geostopping (casing, coring and TD "picks")
- Horizontal drilling ("biosteering")
- Micropaleontology (forams, ostracods, diatoms etc.)
- Nannopalaeontology (calcareous nannoplankton)
- Palynology (dinoflagellates, acritarchs, spores and pollen)